Lock joint for folding support legs



Oct. 20, 1964 c. K. GUTH 3,153,525

LOCK JOINT FOR FOLDING SUPPORT LEGS Filed April 5, 1963 2 Sheets-Sheet 1 INVENTOR.

CH ESTER K. GUTH ATTORNEY Oct. 20, 1964 c. K. GUTH 3,153,525

LOCK JOINT FOR FOLDING SUPPORT LEGS Filed April 3, 1963 2 Sheets-Sheet 2 IN VEN TOR Fig 2 CHESTER K. GUTH BY ATTORNEY United States Patent 3,153,525 LGCK JOINT FQR FOLDING SUPPQRT LEGS Chester K. Goth, St. Petersburg, Fla, assignor to Oravisual Company, Incorporated, St. Petersburg, Fla., a corporation of Florida Filed Apr. 3, 1963, Ser. No. 270,256 '7 Claims. (Cl. 248-1885) The present invention relates to an improved lock joint structure for folding legs employed to support so called collapsible display stands, easels, tables, and the like, and

is an improvement in the lock joint disclosed in United States patent to De Jen No. 2,638,300.

The principal object of the present invention is the provision of a lock joint for a folding support leg comprising two leg segments pivoted together at adjacent ends so that one may be folded about an axis transversely of the leg to lie alongside the other segment to shorten the leg for 1 storage and which may be swung into end to end alignment with the other segment and locked to provide a rigid elongated leg, the joint structure for the segments having incorporated therein an improved locking device which automatically locks the joint as the segments are brought into end to end alignment and which may be operated to release the joint merely by pressing a key plate or element disposed at the joint structure, thereby facilitating the handling of the device to which the leg is attached during the dismantling thereof.

The invention is directed particularly to a locking device for the joint structure of a supporting leg of the type mentioned which comprises two spaced plate-like arms integral with one leg segment and projecting from the pivoted end thereof so as to lie adjacent to spaced parts of the other leg segment when the segments are brought into end to end alignment, means on the arms and the adjacent leg segment parts inter-engaging to lock the seg-.

ments in alignment, the arms being resiliently flexible laterally to disengage the inter-engaged means and being flexed by a key element having surfaces engaging and flexing the arms by movement of a part of the element therebetwen, the key element being attached to the joint structure so that the arm deflecting part thereof normally engages the arms in a position for entry therebetween.

In the preferred form of the invention the arms are adapted to lie alongside opposite sides of the end of the adjacent leg segment when the segments are aligned, and

the interengaging means comprises a pair of pins projecting from opposite sides of the latter leg segment, which pins may be closely received in openings through the arms and are of such length that the arms yieldingly flex laterally and move over the ends of the pins to bring the openings in registration with the pins to receive them therein by retraction of the arms, and the key element is pivoted to the joint structure and has a thumb pressing area and cam means engaging between the arms to spread the same beyond the pin ends to release the pins when the key element is pressed inwardly of the leg.

Other objects and advantages of the invention will be apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings, wherein FIG. 1 is a perspective view of a display easel embodying the invention with the support legs in their extended positions;

FIG. 2 is a view similar to FIG. 1, but showing the legs of the easel folded for storage or transporting of the easel;

FIGS. 3 and 4 are fragmentary perspective views of a locking joint for one of the supoprt legs of the display easel and showing the leg in broken or folded position and locked in an extended position, respectively; and

FIGS. 5 and 6 are fragmentary, sectional views taken substantially on line 55 of FIG. 4 but on a larger scale and showing the key element in an inoperative and operative position.

Referring to FIGS. 1 and 2, an easel or display stand E is shown which may be similar to that described in the United States Patent Number 2,638,300 mentioned hereinbefore, and it comprises a flat board 10, of asuitable construction, having legs 11, 12 and 13 attached thereto by brackets 14 and which legs are braced by struts 14a in a rigid pyramidal arrangement, as shown. The legs are each formed of two segments pivotally joined at the center of the leg so that the segments may be folded for collapsing the display stand for convenient storage or transporting, as shown in FIG. 2, or one segment may be swung into end to end alignment with the other and locked in that position for erecting the easel as shown in FIG. 1.

Legs 11, 12 and 13, and their joint structures, are each alike and for sake of simplicity only leg 11 and its joint structure is described in detail and it is to be understood that the other legs have corresponding constructions and parts referred to by the same reference characters.

Referring to FIGS. 3 through 6, leg 11 is formed of two segments 11a and 1112 each of which are of semi tubular stock, and which may be of any suitable material such as an aluminum column extruded in a C shape cross section. The two leg segments 11a and 111) are interconnected by a lock joint structure comprising two generally triangular shaped resilient plate-like arms 15, 16 which are each secured to opposite sides of segments 11a by a pair of rivets 17, only one of the pair for attaching arm 15 appears in the drawings. As best seen in FIGS. 3 and 4-, these arms extend beyond the lower end of segment 11a, as viewed in the drawings, and form a continuation of that leg segment which can be yieldingly flexed normal to the planes of the major faces thereof but which are substantially inflexible in the planes of the major faces.

Segment 11b is pivotally secured between arms 15 and 16 through two triangular shaped plates 18 and 19 each secured to opposite sides thereof by two pairs of aligned rivets 20a and Zilb and these plates nest against the insides of arms 15 and 16, as shown. Preferably, spacers (not shown) are between arms 15 and 16 and the adjacent sides of segment 11a to position the arms for the reception of plates 18 and 19 therebetween. Plates 18 and 19 are pivotally attached to arms 15 and 16, respectively, by rivet-type pivots 22 which are axially aligned so that leg segment 11b swings about an axis normal to the median of the leg segment from a position alongside segment 11a, as shown in FIG. 2, to a position in end to end alignment with the latter section, as seen in FIGS. 1 and 4. Rivets 20:: have cylindrical formed heads thereon which project appreciably from opposite outer sides of leg segment 11b and are received in respective recesses provided by openings 25 formed through the lower ends of arms 15 and 16, as seen in FIGS. 4 and 5, and the sides of these rivet heads and the edges of the openings are normal to the major planes of the arms so that when the heads of the rivets are in the openings they inter-engage with the opening edges and lock the arms alongside the segment 11b. Because arms 15 and 16 are rigid in a direction about the pivotal axis of the leg segments the segments are maintained in rigid alignment.

To facilitate movement of the rivet heads 20a to their locking positions in the respective openings 25, the forward edges of the lower portions of arms 15 and 16 are flared outwardly to form camming surfaces 15c and 16c so that as leg segment 11b is swung into end to end alignment with leg segment 11a the flared surface engages the rivet heads 26a and wedge the arms to flex them outwardly and in a direction normal to their major faces so that the pins slide under the arms and into registration with openings 25, at which time the arms snap return to their normal planes to imprison the rivet heads in the openings, as best seen in F316. 5. The camming surfaces 150 and 15s are formed by providing hook shape enlargements on the lower ends of the respective arms and bending those edge portions outwardly along diverging lines, as shown.

The joint structure thus far described is like that disclosed in the aforesaid De Jen patent, and the structure described presently is an improvement which provides a convenient and inexpensive means to unlock the joint structure for folding leg segment 11b alongside leg segment 11a. To this end, a key element or plate 3% is provided which is pivotally supported at one end between rivet type pivots 22 by nibs 39a and 3% formed integral therewith and extending into recesses in the opposed axially aligned rivets so that the plate swings about the same axis as the leg segments pivot. Preferably, the plate has a ridge 3th: formed therein to stiffen the plate longitudinally thereof. The unpivoted end of key plate 3% is curved along opposite edges to provide camming surfaces 31 which are arranged to engage camming surfaces 150 and 160 of arms 15; and 16, respectively, and cooperate therewith to flex or wedge the arms outwardly when the plate is pressed therebetween and toward leg section 11b, thereby moving the portions of the arms in which the openings 25 are formed beyond the heads of rivets 29a and 20b to free the rivet heads from the confines of the openings, as may be clearly seen in FIG. 6, so that the leg segments can be folded relative to one another about their pivot. The edges of element 3%) which form cam surfaces 31 are bent along lines approximately parallel to the lines along which surface 150 and 160 are bent and when leg ill is in its extended supporting position as shown in FIGS. 1 and 4, the cam edges of plate 3i rest by gravity on cam surfaces 150 and 16c of the arms 15 and 16, as seen in FIG. 5, so that the key element is in position for imediate action to release the arms from the rivet heads Zita.

It will be seen that to unlock the leg joints to dismantle the easel, a person need only grasp a leg adjacent to the joint structure and with his thumb on the key plate at the portion between the edges 31 thereof and his fingers extending about the opposite side of the leg the key plate can be easily pressed by his thumb to quickly and simply unlock the joint while firmly grasping the leg being collapsed.

It is apparent that the user of the display can quickly eifect unlocking of a leg joint as the support leg is being grasped whereby the folding of the legs and dismantling of the easel is materially facilitated.

It will be appreciated that although I have described but one form of the invention, other forms, modifications, and adaptations could be made, all falling within the scope of the claims which follow. It will be appreciated that although the leg segments 11a and 1112 are shown locked in a straight angle (180) they could be locked at other angles as desired.

Having described my invention, 1 claim:

1. A lock joint structure for a folding leg or the like comprising two leg segments, means connecting two adjacent ends of said segments together for pivotal movement relative to one another about an axis extending transversely thereof, means to releasably lock said segments in a given angular position relative to one another and comprising an arm attached to one segment and extending alongside a part of the other segment when said segments are in said given position, said arm being resiliently flexible laterally from said part of said other segment, means on said arm and said part of said other segment for locking said other segment in rigid angular relationship to said arm to prevent pivotal movement of said segments about said axis, the last mentioned means comprising a pin and a recessed part for receiving said pin whereby the side walls of said recess engage the sides of said pin to prevent lateral movement therebetween, said pin and recessed part being displaceable relative to one another so that said pin is out of registration with the side walls of said recess by flexing of said arm laterally, a key element movably carried by said leg and positioned for engaging said arm, and camming means actuated by movement of said key element to yieldingly urge said arm laterally to release said locking means.

2. A lock joint structure as defined in claim 1 in which said arm has said recess formed therein and said other segment has said pin projecting therefrom for projecting into the plane of said arm, and said arm having a camming surface engageable with said pin for camming said arm beyond the ends of the respective pins.

3. A lock joint structure as defined in claim 1 in which said key element comprises a plate pivotally carried by said structure and having a part engaging said arm to shift said arm when said element is moved about its pivot in one direction.

4. A look joint structure for a folding leg or the like comprising two leg segments, means interconnecting adjacent ends of said leg segments for pivotal movement about a folding axis extending transversely of said leg, a pair of spaced generally parallel arms projecting from one end of one of said leg segments and alongside opposite sides of the adjacent end of said other segment, said arms being yieldingly flexible laterally of said other segment, means on said arms and said other segment for locking said other segment to said arms to prevent relative movement of said leg segments about said folding axis and comprising a pair of projecting pins and parts having a pair of recesses providing side walls between which said pins are received to prevent lateral relative movement of said pins and the respective recessed parts, a key plate movable between said arms and operative to spread said arms and effect relative displacement of said recessed parts and pins whereby said side walls of said recesses-are moved out of registration with the respective said pins, and means to support said key element on said leg and to guide said element for movement between said arms.

5. A lock joint structure as defined in claim 4 in which said arms have said recesses formed therein and said other segment has said pins projecting from opposite sides for extending into the planes of the respective arms, and said arms have camming surfaces engageable with said pins for camming said arms beyond the ends of the respective pins.

6. A lock joint structure as defined in claim 4 in which said key element has one end pivotally supported to said structure and the other end portion being swingable in a path between said arms and engageable therewith for forcing said arms apart when said element is pressed toward said adjacent leg segment.

7. A lock joint structure as defined in claim 4, in which said end portion of said key element has camming surfaces along opposite edges engaging said arms for urging the latter outwardly of one another when said element is pressed toward the adjacent leg segment.

Dickerson May 26, 1903 De Jen May 12, 1953 

1. A LOCK JOINT STRUCTURE FOR A FOLDING LEG OR THE LIKE COMPRISING TWO LEG SEGMENTS, MEANS CONNECTING TWO ADJACENT ENDS OF SAID SEGMENTS TOGETHER FOR PIVOTAL MOVEMENT RELATIVE TO ONE ANOTHER ABOUT AN AXIS EXTENDING TRANSVERSELY THEREOF, MEANS TO RELEASABLY LOCK SAID SEGMENTS IN A GIVEN ANGULAR POSITION RELATIVE TO ONE ANOTHER AND COMPRISING AN ARM ATTACHED TO ONE SEGMENT AND EXTENDING ALONGSIDE A PART OF THE OTHER SEGMENT WHEN SAID SEGMENTS ARE IN SAID GIVEN POSITION, SAID ARM BEING RESILIENTLY FLEXIBLE LATERALLY FROM SAID PART OF SAID OTHER SEGMENT, MEANS ON SAID ARM AND SAID PART OF SAID OTHER RELATIONSHIP TO SAID ARM TO PREVENT PIVOTAL MOVEMENT OF SAID SEGMENTS ABOUT SAID AXIS, THE LAST MENTIONED MEANS COMPRISING A PIN AND A RECESSED PART FOR RECEIVING SAID PIN WHEREBY THE SIDE WALLS OF SAID RECESS ENGAGE THE SIDES OF SAID PIN TO PREVENT LATERAL MOVEMENT THEREBETWEEN SAID PIN AND RECESSED PART BEING DISPLACABLE RELATIVE TO ONE ANOTHER SO THAT SAID PIN IS OUT OF REGISTRATION WITH THE SIDE WALLS OF SAID RECESS BY FLEXING OF SAID ARM LATERALLY, A KEY ELEMENT MOVABLY CARRIED BY SAID LEG AND POSITIONED FOR ENGAGING SAID ARM, AND CAMMING MEANS ACTUATED BY MOVEMENT OF SAID KEY ELEMENT TO YIELDINGLY URGE SAID ARM LATERALLY TO RELEASE SAID LOCKING MEANS. 